Evaluating the effectiveness of the phosphorus sorption index for estimating maximum phosphorus sorption capacity

Carl H. Bolster, Josh M. McGrath, Emileigh Rosso, Karin Blombäck

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

The single-point P sorption index (PSI), which is defined as the ratio of sorbed P (S) to the log P concentration in soil solution following a single P addition, is often used to estimate maximum soil P sorption capacity (Smax). Although studies have found good correlations between PSI and Smax as determined from fitting the Langmuir model to complete sorption isotherm data, a thorough analysis of the role of added P concentration on this relationship is needed. Our first objective was to investigate the effect of added P concentration on the correlation between PSI and Smax as determined by the Langmuir equation. Our second objective was to determine if S was better than PSI for predicting Smax. Using numerical simulations, we tested the correlation between Smax and PSI for added P concentrations of 75, 100, 150, and 200 mg P L−1. Results of the simulations show that the strength of the correlation between Smax and PSI increases with increasing P concentration. Our results also show that PSI was a better predictor of Smax than S for added concentrations of 75 and 100 mg P L−1, whereas at the higher rates S was a slightly better predictor of Smax and gave a direct estimate of Smax rather than the relative estimate obtained from PSI. Results from P sorption data measured on soils from Maryland and Sweden were consistent with our results from the numerical simulations. Our findings highlight important limitations of using PSI for estimating Smax.

Original languageEnglish
Pages (from-to)994-1005
Number of pages12
JournalSoil Science Society of America Journal
Volume84
Issue number3
DOIs
StatePublished - May 1 2020

Bibliographical note

Publisher Copyright:
© 2020 The Authors. Soil Science Society of America Journal © 2020 Soil Science Society of America

ASJC Scopus subject areas

  • Soil Science

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